the digestive system i d. c. mikulecky professor of physiology virginia commonwealth university
TRANSCRIPT
THE DIGESTIVE SYSTEM I
D. C. MikuleckyProfessor of PhysiologyVirginia Commonwealth University
FUNCTIONS OF THE DIGESTIVE SYSTEM
MOTILITYSECRETIONDIGESTIONABSORPTION
THE DIGESTIVE TRACT
MOUTH AND PHARYNXESOPHAGUSSTOMACHSMALL INTESTINELARGE INTESTINEANUS
THE DIGESTIVE TRACT
LUMEN
MUCOSA
SUBMUCOSALPLEXUS
CIRCULARMUSCLE
MYENTERIC PLEXUS
LOGITUDINAL MUSCLE
EXTRINSICNERVES
INNERVATION OF THE G.I. TRACT
PARASYMPATHETIC
SYMPATHETIC
INTRINSIC
PARASYMPATHETIC
VAGUS: DOWN TO TRANSVERSE COLON. PREGANGLIONIC CHOLINERGIC NEURONS ORIGNINATE IN MEDULLA
PELVIC: BELOW THAT. PREGANGLIONIC CHOLINERGIC NEURONS ORIGNINATE IN SACRAL S.C.
SYMPATHETIC
GANGLIA OUTSDE G. I. TRACT: CELIAC, SUPERIOR AND INFERIOR MESENTERIC
POSTGANGLIONIC ADRENERGIC FIBERS INNERVATE MYENTERIC AND SUBMUCOSAL PLEXUS
INTRINSIC INNERVATION
SUBMUCOSAL PLEXUSMYENTERIC PLEXUSDIFFERENT MEDIATORS: ACh,
Nitric Oxide, VIP, Enkephalins, Serotonin, Substance P
G. I. PEPTIDES
HORMONES
NEUROCRINES
PARACRINES
G. I. HORMONES
GASTRINCHOLECYSTOKININ (CCK)SECRETINGIPMOTILIN
GASTRIN
ENDOCRINE CELLS IN PYLORIC STOMACH
STIMULATED BY PROTEIN IN STOMACHSTIMULATES SECRETION BY PARIETAL
AND CHIEF CELLSSTIMULATES ILEAL MOTILITYRELAXES ILEOCECAL SPHINCTER INDUCES COLONIC MASS MOVEMENTS
SECRETIN
ENDOCRINE CELLS IN DUODENAL MUCOSA ACID IN DUODENAL LUMEN INHIBITS GASTRIC EMPTYING INHIBITS GASTRIC SECRETION STIMULATES AQUEOUS BICARBONATE
SECRETION BY PANCREAS STIMULATES BICARBONATE RICH BILE
SECRETION BYLIVER
CHOLECYSTOKININ
ENDOCRINE CELLS IN DUODENAL MUCOSA FAT AND PROTEIN IN DUODENAL LUMEN INHIBITS GASTRIC EMPTYING INHIBITS GASTRIC SECRETION CAUSES GALL BLADDER CONTRACTION CAUSES RELAXATION OF THE SPHINCTER OF
ODDI CONTRIBUTES TO SATIETY
GASRTIC INHIBITORY PEPTIDE (GIP)
STRUCTURALLY RELATED TO SECRETIN AND GLUCAGON
INHIBITS GASTRIC ACIS SECRETION (PHARMACOLOGICAL DOSES)
STIMULATES INSULIN RELEASE
MOTILITY
THE DIGESTIVE TRACT IS SURROUNDED BY LAYERS OF SMOOTH MUSCLE
THESE MUSCLES ENABLE MIXING AND PROPULSIVE MOVEMENT TO BE CARRIED OUT BY THE DIGESTIVE TRACT
SECRETION
DIGESTION REQUIRES THAT ENZYMES BE SECRETED BY THE PANCREAS AND OTHER ORGANS
MUCOUS SECRETIONS PROTECT THE DIGESTIVE TRACT
ACID IS SECRETED IN THE STOMACHTHERE ARE OTHER SECRETIONS OF
IMPORTANCE
DIGESTION
BREAKING DOWN COMPLEX FOODSTUFFS INTO ABSORBABLE UNITS BY ENZYMES PRODUCED IN THE DIGESTIVE SYSTEM
INVOLVES THE BREAKDOWN OF CARBOHYDRATES, PROTEINS FATS, AND OTHER FOODS
ABSORPTION
ALL OTHER FUNCTIONS SUPPORT THIS ONE
THIS IS HOW WE OBTAIN THE NECESSARY FUEL FOR OUR CELLS
ACCESSORY DIGESTIVE ORGANS
SALIVARY GLANDSEXOCRINE PANCREASBILLIARY SYSTEM: (LIVER AND
GALLBLADDER)
CONTROL OF DIGESTIVE SYSTEM
ExternalInfluences
LocalInfluences
Receptors in Digestive Tract
IntrinsicNervePlexuses
Extrinsic Autonomic Nerves
GIHormones
Smooth muscleExocrine Gland CellsEndocrine Gland Cells
THE MOUTH
INGESTION OF FOOD
CHEWING AND SWALLOWING
SALIVARY SECRETION
CHEWING
CHEWING IS THE FIRST STEP IN THE DIGESTIVE PROCESS
FOOD IS MIXED WITH SALIVA AND BROKEN UP INTO SMALLER PIECES
TASTE BUDS ARE STIMULATED
SALIVARY SECRETION
SALIVARY AMYLASE: DIGESTS CARBOHYDRATE
MOISTENING AND LUBRICATING AGENT ANTIBACTERIAL ACTION: LYSOZYME AND
RINSING SOLVENT FOR TASTE STIMULI SPEECH FACILITATION ORAL HYGENE BICARBONATE BUFFERS NEUTRALIZE ACIDS
Swallowing A PROGRAMMED ALL-OR-NONE REFLEX CHEWING AND MOVING THE BOLUS OF FOOD BACK
IS MANLY VOLUNTARY (STRIATED MUSCLE) PRESSURE OF BOLUS ON PHARYNX TRIGGERS
INVOLUNTARY REFLEX (SMOOTH MUSCLE) TONGUE PREVENTS FOOD FROM MOVING BACK UVULA ELEVATED, SEALING NASAL PASSAGE LARYNX ELEVATES AND CLOSURE OF GLOTTIS RESPIRATION BRIEFLY INHIBITED PHARYNGEAL MUSCLES FORCE BOLUS BACK PERISTALTIC WAVES MOVE BOLUS THROUGH
ESOPHAGUS
PERISTALSIS
RINGLIKECONTRACTIONSWEEPS DOWNTHE ESOPHAGUS
THE STOMACH
ESOPHAGUS
BODY
ANTRUM
GASTROESOPHAGEALSPHINCTER
PYLORIC
SPHINCTER
OXYNTICMUCOSA
PYLORICGLANDAREA
FUNDUS
THE STOMACH
MIXING AND STORAGE ORGANHAS ITS OWN PACEMAKER: SETS
FREQUENCY OF RHYTHMIC PERISTALTIC CONTRACTIONS
PERISTALSIS BECOMES STRONGER IN ANTRUM
MOTILITY IS HIGHLY CONTROLLEDNO ABSORPTION OF FOOD, ONLY
ASPIRIN AND ALCOHOL
FACTORS INFLUENCING GASTRIC MOTILITY
DISTENSION OF STOMACH: INCREASES
FEEDBACK FROM THE SMALL INTESTINE: DECREASES
CONTROL FROM CNSGASTRIN: INCREASES
MIXING MOTIONS IN THE STOMACH
PYLORIC SPHINCTERCLOSED
PERISTALSISBEGINS
MIXING MOTIONS IN THE STOMACH
PYLORIC SPHINCTERCLOSED
PERISTALTIC WAVETRAVELS DOWNWARD
STOMACH EMPTYING
PYLORIC SPHINCTEROPENS
PERISTALTIC WAVETRAVELS DOWNWARD
CHYMESQUIRTEDINTODUODENUM
FACTORS CONTROLLING STOMAC EMPTYING
GASTRIC MOTILITYENTEROGASTRIC REFLEX: VIA
INTRINSIC AND AUTONOMIC NERVES
ENTEROGASTRONES: SECRETIN, CHOLECYSTOKININ (CCK), GASTRIC INHIBITORY PEPTIDE
FACTORS IN SMALL INTESTINE CONTROLLING STOMAC EMPTYING
FATACIDHYPERTONICITYDISTENSION
GASTRIC SECRETIONS
MUCOUS: SURFACE CELLS
MUCOUS: MUCOUS NECK CELLS
HYDROCHLORIC ACID: PARIETAL CELLS
INTRINSIC FACTOR: PARIETAL CELLS
PEPSINOGEN: CHIEF CELLS
GASTRIN: ONLY IN THE PYLORIC GLAND AREA
ACTIVATION OF PEPSIN
CHIEFCELL
PEPSIN-OGEN
HCL
PARIETALCELL
PEPSIN
DIGESTSPROTEIN
STIMULATION OF GASTRIC SECRETION: CEPHALIC PHASE
SEEING,SMELLING,TASTINGFOOD
VAGUS INTRINSIC NERVES
PYLORIC AREA
PARIETAL& CHIEFCELLS
GASTRININCREASEDGASTRICSECRETION
STIMULATION OF GASTRIC SECRETION: GASTRIC PHASE
STIMULIIN STOMACH:PROTEIN, DISTENSION,CAFFEINE,ALCOHOL
VAGUSINTRINSIC NERVES
PYLORIC AREA
PARIETAL& CHIEFCELLS
GASTRININCREASEDGASTRICSECRETION
THE GASTRIC MUCOSAL BARRIER
PROTECTS THE CELLS FROM CONTENTS OF STOMACH
LUMINAL MEMBRANES OF CELLS ARE IMPERMEABLE TO PROTONS
CELLS ARE TIGHTLY ADJOINEDRAPID TURNOVER IF BROKEN, PEPTIC ULCER MAY
RESULT: POSITIVE FEEDBACK INVOLVING HISTAMINE
GASTRIN SECRETION INHIBITION
ACID IN ANTRUM
REMOVAL OF PROTEIN AS STOMACH EMPTIES